BELLEVUE, Wash. -

William Lyon Homes has announced it is acquiring Bellevue-based Polygon Northwest for $520 million in cash.

The Seattle Times reports that Polygon has built nearly 16,000 homes in the Seattle and Portland, Oregon, areas since 1991. The new owners say they will keep the Polygon brand name and its 130 employees.

The sale was announced Monday. After it goes through sometime in the third quarter, William Lyon will control more than 18,000 lots in the West, 2,169 of them in the Seattle area.

Chief Executive Bill Lyon said William Lyon Homes, based in Newport Beach., Calif., has been looking to get into the Northwest market for a long time.